The present invention generally relates to a system and method for noise control and damage detection in a wind turbine. In particular, the present invention relates to a system and method to control the noise generated by the wind turbine or detect damage by sensing acoustical emissions.
Recently, wind turbines have received increased attention as an environmentally safe and a relatively inexpensive alternative energy source. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient.
Generally, a wind turbine can include a plurality of blades coupled to a generator rotor through a hub. The generator rotor can be mounted within a housing or nacelle, which may be positioned on top of a tubular tower or a base. The hub and blades may form a wind turbine rotor. Utility grade wind turbines (for example, wind turbines designed to provide electrical power to a utility grid) can have large wind turbine rotors (for example, about thirty or more meters in diameter). Blades on these wind turbine rotors can transform wind energy into a rotational torque or force that drives the rotor of one or more generators, rotationally coupled to the rotor. However, the rotation of the blades can produce undesirable noises.
One known method of reducing the noise generated by the wind turbine is to disable or derate the entire system, thereby preventing or reducing the generation of noise. However, disabling or derating the entire system also prevents the system from producing the desired amount of energy. Another known technique to reduce noise in the system is through mechanical modifications to the system. For example, noise-insulating coatings may be applied to the system and any housings encasing such components to reduce noise generated. Alternatively, the system can be manufactured with noise-absorbing or noise attenuating features. However, the use of noise-insulating coatings, noise-absorbing features, and/or noise-attenuating features are expensive and add significant complexity and expense to the system and do not permit reduction of noise in response to changing external conditions. Furthermore, the noise-insulating coatings, noise-absorbing features, and/or noise-attenuating features do not adequately shield from noise generated by the rotation of the blades.